1. Field of the Invention
This invention generally relates to circuit interrupter apparatus and, more particularly, to an improved contact arm stop structure for a molded case circuit breaker of the low-voltage type.
2. Description of the Prior Art
In order to prevent damage to the operating components or housing when the contacts are rapidly blown open during current overload conditions, it is the common practice in the low-voltage molded case circuit breaker art to employ a so-called "dead rubber" stop that is secured to the cover component of the breaker housing (or to the breaker handle) and is so located that it is struck by the rapidly moving contact arm. The resiliency of the stop provides a cushioning effect which dissipates the kinetic energy of the contact arm and arrests its motion in a very effective manner.
While such resilient stops were generally satisfactory from a functional standpoint, they required the use of a relatively large block of rubber and thus increased the material cost of the breaker. They also increased the handle tooling cost when the stop was attached to this part of the breaker. In addition, the location of the prior art stops at the top of the circuit breaker housing inherently restricted the travel distance of the movable contact arm and thus reduced the gap separating the opened contacts when the circuit breaker was tripped. It is, of course, desirable to have a contact gap as large as possible since this permits the arc between the contacts to be rapidly quenched when the breaker is operated.